This invention relates to saw blade configurations, and more particularly to a saw blade having a raised, non-cutting, fracturing member amongst or adjacent to the saw teeth to facilitate the cutting and raking actions of the saw blade through friable, heterogeneous materials such as soft snow mixed with denser layers of compacted snow and ice.
In the field of avalanche safety research and practice, a snow saw is a vital tool. Snow must be cut cleanly and evenly for the purpose of determining slope stability and snowfall history, Outdoor recreationalists also use saws to build snow caves, igloos, sculptures, emergency shelters, and ski jumps. For these purposes a carpenter saw, timber saw, agricultural saw and machete-like tool have been used. More recently, lightweight, portable hand saws designed solely for the purpose of cutting snow have become available for both recreational and professional use.
Snow is an extremely heterogeneous, crystalline material. There are many factors that effect the snow pack vertical profile, such as number of snowfall events and amount of snow which is deposited with each event. The temperature, wind, humidity and time between events also play a critical role in the development of a various layers can be light and fluffy, solid ice, or anything between these two extremes. If the surface of fresh snow is melted by elevated temperatures, rain, and/or freezing rain and then refrozen or packed hard by a strong wind, it can become much more dense and hard than the snow below it. Subsequent snow deposition events can bury the hard layer within the snow pack. In either case, when the saw encounters this hard icy layer, the teeth of the saw can ride, slip, or skate over the edge of the icy layer, slowing or ceasing the forward cutting progress of the saw. Continued sawing on a hard layer may eventually generate enough friction to melt the ice, but unless the obstructing layer is shattered, the saw will cut more slowly or not at all.
Unlike metal and wood saws, the teeth of which are designed to cut, shave and remove small pieces from the work-piece, snow saws function by shattering the friable crystalline structure of the snow and pushing it out of the way or removing it entirely from the kerf. A layer that is too hard for the teeth to shatter can slow or entirely stop the forward cutting progress of the saw.
The newest generation of snow saws have various tooth designs that address the challenges of cutting heterogeneous snow, namely, widely spaced teeth with relatively dull edges for safety. They are designed to cut and remove the maximum amount of material with the least amount of work and danger to the operator. The object of this invention is to provide a projecting, non-cutting, fracturing member amongst or adjacent to the cutting saw teeth to facilitate the cutting and raking actions of the saw blade through any friable, heterogeneous material. These materials include snow mixed with denser layers of compacted snow and ice, and may also include, but are not limited to, construction materials such as fiber reinforced foam and insulating foam with a stucco exterior.
In its basic concept, this invention provides a saw blade having a projecting, non-cutting, fracturing member or a plurality of projecting, fracturing members interrupting the extending line of cutting saw teeth of the blade, to impact upon obstructions in a heterogeneous work piece as the blade saws through the material. The purpose of the fracturing member is to momentarily interrupt sawing engagement of the cutting saw teeth with an impacting contact against the surface being cut in order to fracture, shatter, roughen and break-up obstructions in the material to increase the ability of the cutting teeth of the saw blade to make forward cutting progress, thereby facilitating the sawing process.
Accordingly, several objects and advantages of this invention are:
To provide a saw blade that will saw more quickly and with less force through various heterogeneous materials including but not limited to snow.
To provide a saw blade that will saw more quickly and with less force through heterogeneous materials comprised of softer less dense matrix mixed with harder friable, fibrous, and/or fragile layers.
To provide a saw blade that can be used in various forms of saws such as linear, circular, reciprocating, continuous band and orbital.